The present invention relates to the fabrication of boat hulls from various synthetic resin materials and, more specifically, to a novel method and apparatus for fabricating high strength boat transoms. Most contemporary boat hulls, measuring from a few feet up to 100 feet or more in length, are fabricated from some form of fiberglas reinforced polyester resin. It is still a widespread practice in the industry, however, to fabricate the transom out of marine or exterior grade plywood with layers of fiberglas and resin on each face. After comparatively few years of usage, small leaks develop in the plastic skin and fastener holes, causing water to be soaked up by the plywood core. This leads to delamination and ultimately rotting of the plywood, with consequent failure of the transom. The problem is particularly acute in boats where large high-powered outboard, or inboard-outboard, motors are mounted on or through the transom.